There were two ways to drive the wheels: either directly via gears, or using generator-driven
traction motors.
Direct drive Argentina The route from
Tucumán to
Santa Fe, Argentina goes through mountainous terrain with few opportunities to take on water. In 1925 the Swedish firm
NOHAB built a turbine locomotive similar to
Fredrik Ljungström's first design. The condenser worked quite well - only 3 or 4% of the water was lost en route and due only to leakage from the tank. The locomotive had reliability problems and was later replaced by a condenser-equipped piston steam locomotive.
France Two attempts were made in
France. One effort, the Nord Turbine, resembled the
LMS Turbomotive in both appearance and mechanical layout. The project was canceled and the locomotive was built as a compound piston steam locomotive instead. The second attempt,
SNCF 232.Q.1, was built in 1940. It was unusual in that its
driving wheels were not connected by
side rods. Each of its three driving axles had its own turbine. It was heavily damaged by German troops in
World War II and was scrapped in 1946.
Germany Multiple attempts at this type were made by
German locomotive builders. In 1928
Krupp-
Zoelly built a geared steam turbine locomotive. The exhaust of the turbine was fed to a
condenser which both conserved water and increased the
thermal efficiency of the turbine. Draught for the fire was provided by a steam-driven fan in the
smokebox. In 1940, this locomotive was hit by a bomb. It was withdrawn from service and not repaired. A similar machine was built by
Maffei in 1929. Despite having a higher-pressure boiler, it was less efficient than the Krupp-Zoelly locomotive. It was hit by a bomb in 1943 and removed from service.
Henschel converted a normal
DRG Class 38 steam locomotive to use a steam turbine in 1927. The locomotive itself was little modified, the major changes being to the
tender which was fitted with coupled driving wheels in a 2-4-4 layout, driven by separate
forward and
reverse turbines. Both turbines were driven by intermediate-pressure exhaust steam from the original cylinders. A condenser in the tender provided a vacuum for the turbine exhaust, increasing thermal efficiency. As the final exhaust was at negligible pressure, the original smokebox blastpipe had to be replaced by an electric draught fan in the smokebox. Performance was disappointing, and the turbine tender was removed in 1937.
Italy Giuseppe Belluzzo of
Italy designed a number of experimental turbine locomotives. None were ever tested on main lines. His first was a small locomotive with four wheels, each fitted with its own small turbine. Reverse movement was accomplished by feeding steam into the turbines via a backwards-facing inlet. Steam turbines are designed to rotate in only one direction, making this method very inefficient. No one else appears to have attempted it. Belluzzo contributed to the design of a
2-8-2 locomotive built by
Ernesto Breda in 1931. It used four turbines in a
multiple expansion arrangement. Belluzzo's US patent from that period shows the turbine driving a
jackshaft through a gearbox in front of the locomotive's drivers. This locomotive was never completely fitted out. In 1933, a
FS Class 685 2-6-2 locomotive was the object of a curious experiment, in which the piston engine was removed and a turbine fitted in its place, leaving the locomotive otherwise completely unchanged. Tests run were however a failure, as its performance proved to be well below that of a normal 685; the turbine soon broke up, and that signalled the end of the attempt. In 1936 the locomotive was refitted with a normal piston engine.
Sweden of 1921
Swedish engineer
Fredrik Ljungström designed a number of steam turbine locomotives, some of which were highly successful. His first attempt in 1921 was a rather odd-looking machine. Its three driving axles were located under the tender, and the cab and boiler sat on unpowered wheels. As a result, only a small portion of the locomotive's weight contributed to
traction. In the mid-1920s, Ljungström filed a patent on a
quill drive for a steam turbine locomotive. The second design was a
2-8-0 similar to a successful freight design. Built in 1930 and 1936 by
Nydqvist & Holm, these locomotives replaced conventional ones on the
Grängesberg-Oxelösund Railway. No condenser was fitted, as its complexity outweighed its
thermodynamic advantages. The wheels were driven by a
jackshaft. These engines were not retired until the 1950s when the line was
electrified. Three engines of this type were built, all three of which have been preserved. These can currently be seen in the
Railway Museum of Grängesberg, two (71 and 73) being owned by the Grängesbergbanornas Järnvägsmuseum (GBBJ) and the third (72) by the
Swedish Railway Museum.
Switzerland The
Swiss firm
Zoelly built a turbine locomotive in 1919. It was a
4-6-0 locomotive fitted with a condenser. It was fitted with a cold-air blower feeding into the
firebox grate rather than a suction fan in the smokebox. This avoided the complexity of building a fan that could withstand hot, corrosive gases, but introduced a new problem. The firebox was at
positive pressure, and hot gases and cinders could be blown out the firebox doors if they were opened while the blower was operating. This potentially dangerous arrangement was eventually replaced with a smokebox fan.
United Kingdom ;
Turbomotive One of the more successful turbines operated in the
United Kingdom, the
LMS Turbomotive, built in 1935, was a variation of the
Princess Royal 4-6-2 large passenger express locomotive. There was no condenser. Although a disadvantage for thermal efficiency of the turbine, it allowed the turbine exhaust to still be used through a blastpipe to draw the fire, as for a conventional steam locomotive and avoiding the separate draught fans that caused so much trouble for other turbine locomotives. Despite this limitation, it had greater thermal efficiency than conventional locomotives. The high efficiency mainly resulted from the fact that there were six steam nozzles directed into the turbine which could be turned on and off individually. Each nozzle could thus be allowed to operate, or not, at full power, rather than being inefficiently throttled to a lower pressure. A certain amount of inspiration appears to have come from
Fredrik Ljungström's turbines in Sweden. The main turbine failed after eleven years in heavy service. The Turbomotive was converted to piston drive in 1952, renamed "Princess Anne" and shortly after entering service was withdrawn following the deadly
Harrow and Wealdstone rail crash in 1952. ; Other designs Another locomotive was built by
Beyer, Peacock and Company, using the
Ljungström turbine by
Fredrik Ljungström. Like one of Ljungström's early designs, the driving wheels were under the tender. Performance was disappointing, however, partly because of poor heating of the boiler. The Reid-Ramsey locomotive (described below) was rebuilt by the
North British Locomotive Company, replacing its electrical transmission with a direct drive from the turbine. Only a few tests were done before it was abandoned due to mechanical failures.
United States 6200 in a PRR promotional image In the waning years of steam, the
Baldwin Locomotive Works undertook several attempts at alternative technologies to diesel power. In 1944, Baldwin built the sole example of the
S2 class for the
Pennsylvania Railroad, delivering it in September 1944. It was the largest direct-drive steam turbine locomotive in the world and had a
6-8-6 wheel arrangement. It was originally designed as a 4-8-4, but due to shortages of lightweight materials during World War II, the S2 required additional
leading and
trailing wheels. Numbered 6200 on the PRR roster, the S2 had a maximum power output of 6,900 HP (5.1 MW) and was capable of speeds over . With the tender, the unit was approximately long. The steam turbine was a modified marine unit. While the gearing system was simpler than a generator, it had a fatal flaw: the turbine was inefficient at slow speeds. Below about the turbine used enormous amounts of steam and fuel. At high speeds, however, the S2 could propel heavy trains smoothly and efficiently. The smooth turbine drive put far less stress on the track than a normal piston-driven locomotive. However, poor efficiency at slow speeds doomed this turbine, and with
diesel–electrics being introduced, no more S2s were built. The locomotive was retired in 1949 and scrapped in May, 1952.
Electric transmission United Kingdom The Reid-Ramsey turbine, built by the
North British Locomotive Company in 1910, had a
2-B+B-2 (
4-4-0+
0-4-4) wheel arrangement. Steam was generated in a standard locomotive boiler, with superheater, and passed to a turbine generator. Exhaust steam was condensed and recirculated by small auxiliary turbine pumps. The
armatures of the motors were mounted directly on the four driving axles. It was later rebuilt as a direct-drive turbine locomotive as noted above. The
Armstrong Whitworth turbine, built in 1922 (image right), had a
1-C+C-1 (
2-6-6-2) wheel arrangement. It was fitted with a rotary evaporative condenser, in which the steam was condensed by passing it through a rotating set of tubes. The tubes were dampened and cooled by the evaporation of water. The loss of water from evaporation was far less than what it would have been with no condenser at all. The airflow in the condenser had to take a convoluted path, reducing the condenser's efficiency. The locomotive was overweight and a poor performer. It was returned in 1923 and scrapped.
United States ;General Electric GE steam turbine locomotives in April 1939
General Electric built two steam turbine–electric
locomotives with a
2+C-C+2 (
4-6-6-4) wheel arrangement for the
Union Pacific in 1938. These locomotives essentially operated as mobile
steam power plants and were correspondingly complex. They were the only
condensing steam locomotives ever used in the United States. A
Babcock & Wilcox boiler provided steam, which drove a pair of
steam turbines which powered a
generator, providing power to the electric
traction motors that drove the wheels, as well as providing
head-end power for the rest of the train. Boiler control was largely automatic, and the two locomotives could be connected together into a
multiple unit, both controlled from a single cab. The boiler was oil-fired, and the fuel was "Bunker C"
heavy fuel oil, the same fuel used in large vessels, and also the fuel which was later used in Union Pacific's
gas turbine–electric locomotives. Union Pacific accepted the locomotives in 1939, but returned them later that year, citing unsatisfactory results. The GE turbines were used during a motive power shortage on the
Great Northern Railway in 1943, and appear to have performed quite well. However, by the end of 1943, the wheels of both locomotives were worn to the point of needing replacement, and one of the locomotive's boilers developed a defect. The locomotives were returned to GE and dismantled. ;C&O Railway In 1947–1948 Baldwin built three unusual
coal-fired steam turbine–electric locomotives for passenger trains on the
Chesapeake & Ohio Railway (C&O). Their designation was M1, but because of their expense and poor performance they acquired the nickname "Sacred Cow". The units, which had
Westinghouse electrical systems, had a
2-C1+2-C1-B wheel arrangement. They were 106 feet (32 m) long. The cab was in the center with a coal bunker ahead and a conventional boiler behind it, with the tender only carrying water. These locomotives were intended for a route from
Washington, D.C. to
Cincinnati, Ohio but could never travel the whole route without some sort of failure.
Coal dust and water frequently got into the traction motors. While these problems could have been fixed given time, it was obvious that these locomotives would always be expensive to maintain and all three were scrapped in 1950. ; locomotive 2300, "Jawn Henry" In May 1954 Baldwin built a steam turbine–electric locomotive for freight service on the
Norfolk & Western Railway (N&W), nicknamed the
Jawn Henry after the legend of
John Henry, a rock driller who famously raced against a steam drill and won, only to die immediately after. Length including tenders was 161 ft inches, probably the record for a steam locomotive; engine-only length was 111 ft inches, perhaps the record for any single unit. The unit looked similar to the C&O turbines but differed mechanically; it was a
C+C-C+C with a
Babcock & Wilcox water-tube boiler with automatic controls. The boiler controls were sometimes problematic, and (as with the C&O turbines) coal dust and water got into the motors. The
Jawn Henry was retired from the N&W roster on January 4, 1958. == References ==